Heartland virus (HRTV) is a Bunyaviridae, phlebovirus that it has
recently emerged as the causative agent of human disease characterized
by thrombocytopenia and leukopenia in the United States and China. It
seems to be the HRTV has been also reported in China, Japan and Korea.
Recently the first fatal case of HRTV disease in an 80-year-old
Tennessee resident was reported (1).

Amblyomma americanum and Dermacentor variabilis ticks have been
involved as a vector of HRTV in USA. The vertebrates amplification hosts
associated with enzootic maintenance of the HRTV have been studied in
Missouri. Neutralizing antibodies to HRTV in raccoons (42.6%), horses
(17.4%), white-tailed deer (14.3%), dogs (7.7%) and opossums (3.8%) were
identified. No antibodies were found in birds. The high seroprevalence
associated with local abundance of white-tailed deer and raccoons
demonstrated these species may be an amplification hosts. Virus
isolation experiments from sera and ticks to detect HRTV virus were
unsuccessful (2).

In 2012 in Missouri farms, 56.428 ticks of Amblyomma americanum and
Dermacentor variabilis were collected. By using RT-PCR (reverse
transcription-polymerase chain reaction), several nymphs pools of A.
americanum were positive, 8 pools yielded viable viruses. Sequence data
from the nonstructural protein of the small segment demonstrates that
tick strains and human strains are very similar, >97.6% sequence
identity (3).

This was the first study to isolate HRTV from ticks and they seem
to be implicating as potential vectors. Amblyomma americanum possible to
becomes infected by feeding on viremic hosts during the larval stage,
and transmission to humans occurs during the spring and early summer
when nymphs are abundant and actively host seeking (3).

A seroprevalence survey performed in Minnesota, USA, tested blood
samples from domestic animals to determine antibodies to HRTV.
Antibodies against virus nucleoproteins in 10%18% of samples from
cattle, sheep, goats, deer, and elk in Minnesota counties were found
(4).

Most patients with HRTV show fever, thrombocytopenia, leukopenia
fatigue, anorexia, headache, nausea, myalgia, or arthralgia. A
clinically compatible disease have been defined as fever ([greater than
or equal to] 38.0[degrees]C), leukopenia (white blood cell count <
4.500 cells/[mm.sup.3]; normal range = 4.500-12.000 cells/[mm.sup.3]),
and thrombocytopenia (platelet count <150.000/[mm.sup.3]; normal
range =150.000-400.000/ [mm.sup.3]) without a more probably clinical
explanation. Physicians in Colombia and Latin America should recognize
Heartland virus testing in patients who show fever, leukopenia, and
thrombocytopenia without more likely evidence and who have tested
negative for Ehrlichia, Anaplasma and Babesia infection or have not
responded to doxycycline therapy (5).

Recently, there was a report of the first fatal case of HRTV
disease in an 80-year-old Tennessee resident. The patient was admitted
at the clinic with fever, confusion, leukopenia, and thrombocytopenia
and developed multiorgan failure and hemorrhage. The patient died on
hospital day 15, and autopsy specimens were tested for various pathogens
as part of an unexplained death evaluation. HRTV antigens were detected
in postmortem spleen and lymph nodes by immunohistochemistry, and HRTV
was detected in premortem blood by RT-PCR and the virus was isolated in
cell culture (6).

Because HRTV is an emerging virus, laboratory diagnosis is
incipient yet, the diagnosis in Colombia and Latin America is extremely
difficult. However, detection of viral RNA by RT-PCR on blood or tissue
can be carry out, hence a [greater than or equal to] 4-fold rise
antibody titers by PRNT in acute and convalescent serum specimens can be
carry out (5).

Like other viruses, no vaccine or medication is available to
prevent or treat Heartland virus disease. Because the virus possible is
transmitted through infected ticks or other arthropods, prevention
depends on using insect repellents, wearing long sleeves and pants and
performing tick checks after spending time outdoors (5).

In Colombia especially in the tropics, there are strong evidence of
Amblyomma sp and Dermacentor ticks thus, it is likely that HRTV is
circulating. The fatal cases in USA demonstrate that HRTV infection can
cause severe disease and death. In Colombia, tick's population are
endemic affecting animals and people, the dissemination of the HRTV in
Colombia is likely because the favourable geoclimatic conditions (7).

Finally, tick-borne viruses that cause diseases in humans mainly
belong to 3 families: Bunyaviridae, Flaviviridae, and Reoviridae, we
actually in Latin America do not know about this vector borne disease,
it is necessary to carry out several surveys to establish the prevalence
of those viruses in the vectors and humans as well.